I welcome thoughts, criticisms, etc.

What audience are you writing for? Your current writing style has the advantage that it is relatively clear and gives you an enviable air of objectivity, but the disadvantage that it's somewhat emotionless. Compared to, say, Eliezer's writing, it's hard to get a sense for how much you care about the points you're making. This is an issue if you intend to reach a broad-ish audience but less of an issue if your intended audience is people approximately as good at taking ideas seriously as you are.

I don't really understand your argument about progress. Right now it reads to me like "assuming that net progress is approximately zero, we conclude that net progress is approximately zero."

In particular, for a broad range of values, the first thing to do is to establish a stable, technologically sophisticated civilization at a large scale, which can then direct its action on the basis of careful argument and reflection.

This is unclear to me unless you say something about how coordination problems are solved in such a civilization. Increasing the scale of civilization increases the scale of the coordination problems you need to solve, which is not obviously a good thing. Plausibly a civilization which is too large may face coordination problems too intractable to make certain kinds of changes which may end up being extremely valuable. (Plausibly we already live in such a civilization.)